Pelizaeus-Merzbacher disease is a rare sex-linked leukodystrophy. Its metabolic basis has not been identified yet and diagnosis in mainly based on clinical findings and pathological investigation. Cerebral biopsy is not always performed because of lack of available therapy. Genetic counseling can be provided if the diagnosis is secured. Four cases are reported, in children with characteristic signs, who underwent magnetic resonance (MR) Imaging. MR Imaging appears to be more sensitive than computed tomography to visualize white matter disease: T1 weighted images suggest hypomyelination, in conformity with abnormal myelination. T2 weighted images show a non specific high signal in the white matter.